Stable-surface alloy steel



I 30 put.

Patented July 1, 1930 PATENT OFFICE RALPH I.'DE V'BIES, F NEWTONVILLE, NEW YORK STABLE-SURFACE ALLOY srnnr.

No Drawing.

This invention relates to alloys of steel, and more particularly to such alloys as are known to the trade as stable surface alloy steels.

The main objects of my invention are to provide an alloy steel of new composition which will be resistant to scaling action at high temperatures and which shall have a fine grain, fair strength, and good ductility when high percentages of aluminum are the essential and in most cases the main ingredient of said alloy.

To the best of my knowledge it'has heretofore never been possible to use for general engineering and structural purposes, any

alloy which contains aluminum in the ranges of 1% to 6%, for the reason that any alloy containing quantities of aluminum in the proportions just mentioned, cannot be manufactured into bars, strips, and other commercial grades of steel, although it has been possible through the use of various combinations of other alloying metals with aluminum to obtain sufiicient malleability, so that such steel when cast into ingot form, can be successfully rolled and worked. It has not been found that such alloys are of a strength and ductility requisite for the utilities to which the present alloy may be I have found that by alloying copper and chromium with aluminum in the steel, a product of remarkable characteristics is obtained. This product is especiallypseful for internal combustion engine poppet valves, electrical resistance heating elements, carburizing boxes, and for other purposes wherein metal is desired which wlll resist scaling particularly at high tempera- 140 tures.

I have found that an alloy steel of thev present composition, when in ingot form discloses, on fracture, a structure having very large crystals. These ingots, however, whlch apparently possess all the inherent disadvantages characteristic of other steel alloys containing high percentages of aluminum, undergo on hammering and rolling, a remarkable transformation. The bars formed fromsuch ingom have a remarkably Application filed January 20, 1926. Serial No. 82,610.

fine grain, whether the reducing work is done either by hammering or by rolling. The bars furthermore have good physical properties, both from a standpoint of strength and ductility.

From the microscopic appearance of ingot sections, it may be readily seen that the function of the copper 'is to form a solid solution with the aluminum. The presence of this solid solution, indicates that the aluminum is not present in the alloy in the form of a mechanical mixture. This I believe accounts for the fact that the bars rolled from ingots possess fine grain and good physical properties.

An alloy steel made in accordance with my invention contains chromium from 1.0% to 10.0%, aluminum from 1.0% to 6.0%, and copper from 0.5% to 5.0%. Ihave discovered that where the minimum of chromium (i. e 1.0%) is used the permissible minimum of aluminum and copper together is 3.0%, and of this 3.0% at least two-thirds must be aluminum. All proportions given are percentages of the whole by weight.

Alloys of this composition can be melted practically carbon free but for some purposes may contain carbon The usual amount of manganese found in tool and structural steels may be present,

or slightly greater amounts up to 1.5% may be used. Impurities and metalloids such as sulphur, phosphorus, etc., will be kept as low as possible. Typical examples of this alloy may be noted as having the following compositions I Aluminum Chromium Copper Carbon Iron Per cent Per cent Per cent Per cent 2.00 4.00 3.00 0.27 Balance. 1. 36 4. 00 2. 00 0. 41 Balance. 4. 24 4. 31 2. 57 0. 35 Balance.

as highas 1%.-

cal properties by heat treatment which may consist of hardening as mentioned and drawing thesteel by reheating after such hardening.

I claim 1. As a new product, an alloy steel comprising chromium from 1.0% to 10.0%,'

aluminum from 1.0% to 6.0%, copper from 0.5% to 5.0%, carbon from 0.05% to 1.0%, and the balance/iron.

2. An alloy steel comprising as essentials of the alloy, chromium from 1.0% to 10.0%,

aluminum from 1.0% to 6.0%, and copper.

= from 0.5% to 5.0%.

3. An alloy steel comprising as essentials of the alloy, chromium from 1% to 10%, aluminum from 1% to 3%, and copper from 0.5% to 5%.

4. A stable surface alloy having, as alloying elements, about l.to 10% of chromium, about 1 to 6% of aluminum, about 0.5 to 5% of copper and up to about 1% of carbon, the balance being mainly iron.

5. A stable surface alloy having about 1% of chromium, about 2% of aluminum and about 1% of copper, the balance being mainly iron. 7

In testimony whereof I havesigncd my name to this specification.

' f RALPH P. DE VRIES. 

